ddp.c

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/*
 *  DDP:    An implementation of the AppleTalk DDP protocol for
 *      Ethernet 'ELAP'.
 *
 *      Alan Cox  <[email protected]>
 *
 *      With more than a little assistance from
 *
 *      Wesley Craig <[email protected]>
 *
 *  Fixes:
 *      Neil Horman     :   Added missing device ioctls
 *      Michael Callahan    :   Made routing work
 *      Wesley Craig        :   Fix probing to listen to a
 *                      passed node id.
 *      Alan Cox        :   Added send/recvmsg support
 *      Alan Cox        :   Moved at. to protinfo in
 *                      socket.
 *      Alan Cox        :   Added firewall hooks.
 *      Alan Cox        :   Supports new ARPHRD_LOOPBACK
 *      Christer Weinigel   :   Routing and /proc fixes.
 *      Bradford Johnson    :   LocalTalk.
 *      Tom Dyas        :   Module support.
 *      Alan Cox        :   Hooks for PPP (based on the
 *                      LocalTalk hook).
 *      Alan Cox        :   Posix bits
 *      Alan Cox/Mike Freeman   :   Possible fix to NBP problems
 *      Bradford Johnson    :   IP-over-DDP (experimental)
 *      Jay Schulist        :   Moved IP-over-DDP to its own
 *                      driver file. (ipddp.c & ipddp.h)
 *      Jay Schulist        :   Made work as module with
 *                      AppleTalk drivers, cleaned it.
 *      Rob Newberry        :   Added proxy AARP and AARP
 *                      procfs, moved probing to AARP
 *                      module.
 *              Adrian Sun/
 *              Michael Zuelsdorff      :       fix for net.0 packets. don't
 *                                              allow illegal ether/tokentalk
 *                                              port assignment. we lose a
 *                                              valid localtalk port as a
 *                                              result.
 *      Arnaldo C. de Melo  :   Cleanup, in preparation for
 *                      shared skb support 8)
 *      Arnaldo C. de Melo  :   Move proc stuff to atalk_proc.c,
 *                      use seq_file
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 *
 */

#include <linux/capability.h>
#include <linux/module.h>
#include <linux/if_arp.h>
#include <linux/termios.h>  /* For TIOCOUTQ/INQ */
#include <linux/compat.h>
#include <linux/slab.h>
#include <net/datalink.h>
#include <net/psnap.h>
#include <net/sock.h>
#include <net/tcp_states.h>
#include <net/route.h>
#include <linux/atalk.h>
#include <linux/highmem.h>

struct datalink_proto *ddp_dl, *aarp_dl;
static const struct proto_ops atalk_dgram_ops;

/**************************************************************************\
*                                                                          *
* Handlers for the socket list.                                            *
*                                                                          *
\**************************************************************************/

HLIST_HEAD(atalk_sockets);
DEFINE_RWLOCK(atalk_sockets_lock);

static inline void __atalk_insert_socket(struct sock *sk)
{
    sk_add_node(sk, &atalk_sockets);
}

static inline void atalk_remove_socket(struct sock *sk)
{
    write_lock_bh(&atalk_sockets_lock);
    sk_del_node_init(sk);
    write_unlock_bh(&atalk_sockets_lock);
}

static struct sock *atalk_search_socket(struct sockaddr_at *to,
                    struct atalk_iface *atif)
{
    struct sock *s;
    struct hlist_node *node;

    read_lock_bh(&atalk_sockets_lock);
    sk_for_each(s, node, &atalk_sockets) {
        struct atalk_sock *at = at_sk(s);

        if (to->sat_port != at->src_port)
            continue;

        if (to->sat_addr.s_net == ATADDR_ANYNET &&
            to->sat_addr.s_node == ATADDR_BCAST)
            goto found;

        if (to->sat_addr.s_net == at->src_net &&
            (to->sat_addr.s_node == at->src_node ||
             to->sat_addr.s_node == ATADDR_BCAST ||
             to->sat_addr.s_node == ATADDR_ANYNODE))
            goto found;

        /* XXXX.0 -- we got a request for this router. make sure
         * that the node is appropriately set. */
        if (to->sat_addr.s_node == ATADDR_ANYNODE &&
            to->sat_addr.s_net != ATADDR_ANYNET &&
            atif->address.s_node == at->src_node) {
            to->sat_addr.s_node = atif->address.s_node;
            goto found;
        }
    }
    s = NULL;
found:
    read_unlock_bh(&atalk_sockets_lock);
    return s;
}

static struct sock *atalk_find_or_insert_socket(struct sock *sk,
                        struct sockaddr_at *sat)
{
    struct sock *s;
    struct hlist_node *node;
    struct atalk_sock *at;

    write_lock_bh(&atalk_sockets_lock);
    sk_for_each(s, node, &atalk_sockets) {
        at = at_sk(s);

        if (at->src_net == sat->sat_addr.s_net &&
            at->src_node == sat->sat_addr.s_node &&
            at->src_port == sat->sat_port)
            goto found;
    }
    s = NULL;
    __atalk_insert_socket(sk); /* Wheee, it's free, assign and insert. */
found:
    write_unlock_bh(&atalk_sockets_lock);
    return s;
}

static void atalk_destroy_timer(unsigned long data)
{
    struct sock *sk = (struct sock *)data;

    if (sk_has_allocations(sk)) {
        sk->sk_timer.expires = jiffies + SOCK_DESTROY_TIME;
        add_timer(&sk->sk_timer);
    } else
        sock_put(sk);
}

static inline void atalk_destroy_socket(struct sock *sk)
{
    atalk_remove_socket(sk);
    skb_queue_purge(&sk->sk_receive_queue);

    if (sk_has_allocations(sk)) {
        setup_timer(&sk->sk_timer, atalk_destroy_timer,
                (unsigned long)sk);
        sk->sk_timer.expires    = jiffies + SOCK_DESTROY_TIME;
        add_timer(&sk->sk_timer);
    } else
        sock_put(sk);
}

/**************************************************************************\
*                                                                          *
* Routing tables for the AppleTalk socket layer.                           *
*                                                                          *
\**************************************************************************/

/* Anti-deadlock ordering is atalk_routes_lock --> iface_lock -DaveM */
struct atalk_route *atalk_routes;
DEFINE_RWLOCK(atalk_routes_lock);

struct atalk_iface *atalk_interfaces;
DEFINE_RWLOCK(atalk_interfaces_lock);

/* For probing devices or in a routerless network */
struct atalk_route atrtr_default;

/* AppleTalk interface control */
/*
 * Drop a device. Doesn't drop any of its routes - that is the caller's
 * problem. Called when we down the interface or delete the address.
 */
static void atif_drop_device(struct net_device *dev)
{
    struct atalk_iface **iface = &atalk_interfaces;
    struct atalk_iface *tmp;

    write_lock_bh(&atalk_interfaces_lock);
    while ((tmp = *iface) != NULL) {
        if (tmp->dev == dev) {
            *iface = tmp->next;
            dev_put(dev);
            kfree(tmp);
            dev->atalk_ptr = NULL;
        } else
            iface = &tmp->next;
    }
    write_unlock_bh(&atalk_interfaces_lock);
}

static struct atalk_iface *atif_add_device(struct net_device *dev,
                       struct atalk_addr *sa)
{
    struct atalk_iface *iface = kzalloc(sizeof(*iface), GFP_KERNEL);

    if (!iface)
        goto out;

    dev_hold(dev);
    iface->dev = dev;
    dev->atalk_ptr = iface;
    iface->address = *sa;
    iface->status = 0;

    write_lock_bh(&atalk_interfaces_lock);
    iface->next = atalk_interfaces;
    atalk_interfaces = iface;
    write_unlock_bh(&atalk_interfaces_lock);
out:
    return iface;
}

/* Perform phase 2 AARP probing on our tentative address */
static int atif_probe_device(struct atalk_iface *atif)
{
    int netrange = ntohs(atif->nets.nr_lastnet) -
            ntohs(atif->nets.nr_firstnet) + 1;
    int probe_net = ntohs(atif->address.s_net);
    int probe_node = atif->address.s_node;
    int netct, nodect;

    /* Offset the network we start probing with */
    if (probe_net == ATADDR_ANYNET) {
        probe_net = ntohs(atif->nets.nr_firstnet);
        if (netrange)
            probe_net += jiffies % netrange;
    }
    if (probe_node == ATADDR_ANYNODE)
        probe_node = jiffies & 0xFF;

    /* Scan the networks */
    atif->status |= ATIF_PROBE;
    for (netct = 0; netct <= netrange; netct++) {
        /* Sweep the available nodes from a given start */
        atif->address.s_net = htons(probe_net);
        for (nodect = 0; nodect < 256; nodect++) {
            atif->address.s_node = (nodect + probe_node) & 0xFF;
            if (atif->address.s_node > 0 &&
                atif->address.s_node < 254) {
                /* Probe a proposed address */
                aarp_probe_network(atif);

                if (!(atif->status & ATIF_PROBE_FAIL)) {
                    atif->status &= ~ATIF_PROBE;
                    return 0;
                }
            }
            atif->status &= ~ATIF_PROBE_FAIL;
        }
        probe_net++;
        if (probe_net > ntohs(atif->nets.nr_lastnet))
            probe_net = ntohs(atif->nets.nr_firstnet);
    }
    atif->status &= ~ATIF_PROBE;

    return -EADDRINUSE; /* Network is full... */
}


/* Perform AARP probing for a proxy address */
static int atif_proxy_probe_device(struct atalk_iface *atif,
                   struct atalk_addr* proxy_addr)
{
    int netrange = ntohs(atif->nets.nr_lastnet) -
            ntohs(atif->nets.nr_firstnet) + 1;
    /* we probe the interface's network */
    int probe_net = ntohs(atif->address.s_net);
    int probe_node = ATADDR_ANYNODE;        /* we'll take anything */
    int netct, nodect;

    /* Offset the network we start probing with */
    if (probe_net == ATADDR_ANYNET) {
        probe_net = ntohs(atif->nets.nr_firstnet);
        if (netrange)
            probe_net += jiffies % netrange;
    }

    if (probe_node == ATADDR_ANYNODE)
        probe_node = jiffies & 0xFF;

    /* Scan the networks */
    for (netct = 0; netct <= netrange; netct++) {
        /* Sweep the available nodes from a given start */
        proxy_addr->s_net = htons(probe_net);
        for (nodect = 0; nodect < 256; nodect++) {
            proxy_addr->s_node = (nodect + probe_node) & 0xFF;
            if (proxy_addr->s_node > 0 &&
                proxy_addr->s_node < 254) {
                /* Tell AARP to probe a proposed address */
                int ret = aarp_proxy_probe_network(atif,
                                    proxy_addr);

                if (ret != -EADDRINUSE)
                    return ret;
            }
        }
        probe_net++;
        if (probe_net > ntohs(atif->nets.nr_lastnet))
            probe_net = ntohs(atif->nets.nr_firstnet);
    }

    return -EADDRINUSE; /* Network is full... */
}


struct atalk_addr *atalk_find_dev_addr(struct net_device *dev)
{
    struct atalk_iface *iface = dev->atalk_ptr;
    return iface ? &iface->address : NULL;
}

static struct atalk_addr *atalk_find_primary(void)
{
    struct atalk_iface *fiface = NULL;
    struct atalk_addr *retval;
    struct atalk_iface *iface;

    /*
     * Return a point-to-point interface only if
     * there is no non-ptp interface available.
     */
    read_lock_bh(&atalk_interfaces_lock);
    for (iface = atalk_interfaces; iface; iface = iface->next) {
        if (!fiface && !(iface->dev->flags & IFF_LOOPBACK))
            fiface = iface;
        if (!(iface->dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT))) {
            retval = &iface->address;
            goto out;
        }
    }

    if (fiface)
        retval = &fiface->address;
    else if (atalk_interfaces)
        retval = &atalk_interfaces->address;
    else
        retval = NULL;
out:
    read_unlock_bh(&atalk_interfaces_lock);
    return retval;
}

/*
 * Find a match for 'any network' - ie any of our interfaces with that
 * node number will do just nicely.
 */
static struct atalk_iface *atalk_find_anynet(int node, struct net_device *dev)
{
    struct atalk_iface *iface = dev->atalk_ptr;

    if (!iface || iface->status & ATIF_PROBE)
        goto out_err;

    if (node != ATADDR_BCAST &&
        iface->address.s_node != node &&
        node != ATADDR_ANYNODE)
        goto out_err;
out:
    return iface;
out_err:
    iface = NULL;
    goto out;
}

/* Find a match for a specific network:node pair */
static struct atalk_iface *atalk_find_interface(__be16 net, int node)
{
    struct atalk_iface *iface;

    read_lock_bh(&atalk_interfaces_lock);
    for (iface = atalk_interfaces; iface; iface = iface->next) {
        if ((node == ATADDR_BCAST ||
             node == ATADDR_ANYNODE ||
             iface->address.s_node == node) &&
            iface->address.s_net == net &&
            !(iface->status & ATIF_PROBE))
            break;

        /* XXXX.0 -- net.0 returns the iface associated with net */
        if (node == ATADDR_ANYNODE && net != ATADDR_ANYNET &&
            ntohs(iface->nets.nr_firstnet) <= ntohs(net) &&
            ntohs(net) <= ntohs(iface->nets.nr_lastnet))
            break;
    }
    read_unlock_bh(&atalk_interfaces_lock);
    return iface;
}


/*
 * Find a route for an AppleTalk packet. This ought to get cached in
 * the socket (later on...). We know about host routes and the fact
 * that a route must be direct to broadcast.
 */
static struct atalk_route *atrtr_find(struct atalk_addr *target)
{
    /*
     * we must search through all routes unless we find a
     * host route, because some host routes might overlap
     * network routes
     */
    struct atalk_route *net_route = NULL;
    struct atalk_route *r;

    read_lock_bh(&atalk_routes_lock);
    for (r = atalk_routes; r; r = r->next) {
        if (!(r->flags & RTF_UP))
            continue;

        if (r->target.s_net == target->s_net) {
            if (r->flags & RTF_HOST) {
                /*
                 * if this host route is for the target,
                 * the we're done
                 */
                if (r->target.s_node == target->s_node)
                    goto out;
            } else
                /*
                 * this route will work if there isn't a
                 * direct host route, so cache it
                 */
                net_route = r;
        }
    }

    /*
     * if we found a network route but not a direct host
     * route, then return it
     */
    if (net_route)
        r = net_route;
    else if (atrtr_default.dev)
        r = &atrtr_default;
    else /* No route can be found */
        r = NULL;
out:
    read_unlock_bh(&atalk_routes_lock);
    return r;
}


/*
 * Given an AppleTalk network, find the device to use. This can be
 * a simple lookup.
 */
struct net_device *atrtr_get_dev(struct atalk_addr *sa)
{
    struct atalk_route *atr = atrtr_find(sa);
    return atr ? atr->dev : NULL;
}

/* Set up a default router */
static void atrtr_set_default(struct net_device *dev)
{
    atrtr_default.dev        = dev;
    atrtr_default.flags      = RTF_UP;
    atrtr_default.gateway.s_net  = htons(0);
    atrtr_default.gateway.s_node = 0;
}

/*
 * Add a router. Basically make sure it looks valid and stuff the
 * entry in the list. While it uses netranges we always set them to one
 * entry to work like netatalk.
 */
static int atrtr_create(struct rtentry *r, struct net_device *devhint)
{
    struct sockaddr_at *ta = (struct sockaddr_at *)&r->rt_dst;
    struct sockaddr_at *ga = (struct sockaddr_at *)&r->rt_gateway;
    struct atalk_route *rt;
    struct atalk_iface *iface, *riface;
    int retval = -EINVAL;

    /*
     * Fixme: Raise/Lower a routing change semaphore for these
     * operations.
     */

    /* Validate the request */
    if (ta->sat_family != AF_APPLETALK ||
        (!devhint && ga->sat_family != AF_APPLETALK))
        goto out;

    /* Now walk the routing table and make our decisions */
    write_lock_bh(&atalk_routes_lock);
    for (rt = atalk_routes; rt; rt = rt->next) {
        if (r->rt_flags != rt->flags)
            continue;

        if (ta->sat_addr.s_net == rt->target.s_net) {
            if (!(rt->flags & RTF_HOST))
                break;
            if (ta->sat_addr.s_node == rt->target.s_node)
                break;
        }
    }

    if (!devhint) {
        riface = NULL;

        read_lock_bh(&atalk_interfaces_lock);
        for (iface = atalk_interfaces; iface; iface = iface->next) {
            if (!riface &&
                ntohs(ga->sat_addr.s_net) >=
                    ntohs(iface->nets.nr_firstnet) &&
                ntohs(ga->sat_addr.s_net) <=
                    ntohs(iface->nets.nr_lastnet))
                riface = iface;

            if (ga->sat_addr.s_net == iface->address.s_net &&
                ga->sat_addr.s_node == iface->address.s_node)
                riface = iface;
        }
        read_unlock_bh(&atalk_interfaces_lock);

        retval = -ENETUNREACH;
        if (!riface)
            goto out_unlock;

        devhint = riface->dev;
    }

    if (!rt) {
        rt = kzalloc(sizeof(*rt), GFP_ATOMIC);

        retval = -ENOBUFS;
        if (!rt)
            goto out_unlock;

        rt->next = atalk_routes;
        atalk_routes = rt;
    }

    /* Fill in the routing entry */
    rt->target  = ta->sat_addr;
    dev_hold(devhint);
    rt->dev     = devhint;
    rt->flags   = r->rt_flags;
    rt->gateway = ga->sat_addr;

    retval = 0;
out_unlock:
    write_unlock_bh(&atalk_routes_lock);
out:
    return retval;
}

/* Delete a route. Find it and discard it */
static int atrtr_delete(struct atalk_addr * addr)
{
    struct atalk_route **r = &atalk_routes;
    int retval = 0;
    struct atalk_route *tmp;

    write_lock_bh(&atalk_routes_lock);
    while ((tmp = *r) != NULL) {
        if (tmp->target.s_net == addr->s_net &&
            (!(tmp->flags&RTF_GATEWAY) ||
             tmp->target.s_node == addr->s_node)) {
            *r = tmp->next;
            dev_put(tmp->dev);
            kfree(tmp);
            goto out;
        }
        r = &tmp->next;
    }
    retval = -ENOENT;
out:
    write_unlock_bh(&atalk_routes_lock);
    return retval;
}

/*
 * Called when a device is downed. Just throw away any routes
 * via it.
 */
static void atrtr_device_down(struct net_device *dev)
{
    struct atalk_route **r = &atalk_routes;
    struct atalk_route *tmp;

    write_lock_bh(&atalk_routes_lock);
    while ((tmp = *r) != NULL) {
        if (tmp->dev == dev) {
            *r = tmp->next;
            dev_put(dev);
            kfree(tmp);
        } else
            r = &tmp->next;
    }
    write_unlock_bh(&atalk_routes_lock);

    if (atrtr_default.dev == dev)
        atrtr_set_default(NULL);
}

/* Actually down the interface */
static inline void atalk_dev_down(struct net_device *dev)
{
    atrtr_device_down(dev); /* Remove all routes for the device */
    aarp_device_down(dev);  /* Remove AARP entries for the device */
    atif_drop_device(dev);  /* Remove the device */
}

/*
 * A device event has occurred. Watch for devices going down and
 * delete our use of them (iface and route).
 */
static int ddp_device_event(struct notifier_block *this, unsigned long event,
                void *ptr)
{
    struct net_device *dev = ptr;

    if (!net_eq(dev_net(dev), &init_net))
        return NOTIFY_DONE;

    if (event == NETDEV_DOWN)
        /* Discard any use of this */
        atalk_dev_down(dev);

    return NOTIFY_DONE;
}

/* ioctl calls. Shouldn't even need touching */
/* Device configuration ioctl calls */
static int atif_ioctl(int cmd, void __user *arg)
{
    static char aarp_mcast[6] = { 0x09, 0x00, 0x00, 0xFF, 0xFF, 0xFF };
    struct ifreq atreq;
    struct atalk_netrange *nr;
    struct sockaddr_at *sa;
    struct net_device *dev;
    struct atalk_iface *atif;
    int ct;
    int limit;
    struct rtentry rtdef;
    int add_route;

    if (copy_from_user(&atreq, arg, sizeof(atreq)))
        return -EFAULT;

    dev = __dev_get_by_name(&init_net, atreq.ifr_name);
    if (!dev)
        return -ENODEV;

    sa = (struct sockaddr_at *)&atreq.ifr_addr;
    atif = atalk_find_dev(dev);

    switch (cmd) {
    case SIOCSIFADDR:
        if (!capable(CAP_NET_ADMIN))
            return -EPERM;
        if (sa->sat_family != AF_APPLETALK)
            return -EINVAL;
        if (dev->type != ARPHRD_ETHER &&
            dev->type != ARPHRD_LOOPBACK &&
            dev->type != ARPHRD_LOCALTLK &&
            dev->type != ARPHRD_PPP)
            return -EPROTONOSUPPORT;

        nr = (struct atalk_netrange *)&sa->sat_zero[0];
        add_route = 1;

        /*
         * if this is a point-to-point iface, and we already
         * have an iface for this AppleTalk address, then we
         * should not add a route
         */
        if ((dev->flags & IFF_POINTOPOINT) &&
            atalk_find_interface(sa->sat_addr.s_net,
                     sa->sat_addr.s_node)) {
            printk(KERN_DEBUG "AppleTalk: point-to-point "
                   "interface added with "
                   "existing address\n");
            add_route = 0;
        }

        /*
         * Phase 1 is fine on LocalTalk but we don't do
         * EtherTalk phase 1. Anyone wanting to add it go ahead.
         */
        if (dev->type == ARPHRD_ETHER && nr->nr_phase != 2)
            return -EPROTONOSUPPORT;
        if (sa->sat_addr.s_node == ATADDR_BCAST ||
            sa->sat_addr.s_node == 254)
            return -EINVAL;
        if (atif) {
            /* Already setting address */
            if (atif->status & ATIF_PROBE)
                return -EBUSY;

            atif->address.s_net  = sa->sat_addr.s_net;
            atif->address.s_node = sa->sat_addr.s_node;
            atrtr_device_down(dev); /* Flush old routes */
        } else {
            atif = atif_add_device(dev, &sa->sat_addr);
            if (!atif)
                return -ENOMEM;
        }
        atif->nets = *nr;

        /*
         * Check if the chosen address is used. If so we
         * error and atalkd will try another.
         */

        if (!(dev->flags & IFF_LOOPBACK) &&
            !(dev->flags & IFF_POINTOPOINT) &&
            atif_probe_device(atif) < 0) {
            atif_drop_device(dev);
            return -EADDRINUSE;
        }

        /* Hey it worked - add the direct routes */
        sa = (struct sockaddr_at *)&rtdef.rt_gateway;
        sa->sat_family = AF_APPLETALK;
        sa->sat_addr.s_net  = atif->address.s_net;
        sa->sat_addr.s_node = atif->address.s_node;
        sa = (struct sockaddr_at *)&rtdef.rt_dst;
        rtdef.rt_flags = RTF_UP;
        sa->sat_family = AF_APPLETALK;
        sa->sat_addr.s_node = ATADDR_ANYNODE;
        if (dev->flags & IFF_LOOPBACK ||
            dev->flags & IFF_POINTOPOINT)
            rtdef.rt_flags |= RTF_HOST;

        /* Routerless initial state */
        if (nr->nr_firstnet == htons(0) &&
            nr->nr_lastnet == htons(0xFFFE)) {
            sa->sat_addr.s_net = atif->address.s_net;
            atrtr_create(&rtdef, dev);
            atrtr_set_default(dev);
        } else {
            limit = ntohs(nr->nr_lastnet);
            if (limit - ntohs(nr->nr_firstnet) > 4096) {
                printk(KERN_WARNING "Too many routes/"
                       "iface.\n");
                return -EINVAL;
            }
            if (add_route)
                for (ct = ntohs(nr->nr_firstnet);
                     ct <= limit; ct++) {
                    sa->sat_addr.s_net = htons(ct);
                    atrtr_create(&rtdef, dev);
                }
        }
        dev_mc_add_global(dev, aarp_mcast);
        return 0;

    case SIOCGIFADDR:
        if (!atif)
            return -EADDRNOTAVAIL;

        sa->sat_family = AF_APPLETALK;
        sa->sat_addr = atif->address;
        break;

    case SIOCGIFBRDADDR:
        if (!atif)
            return -EADDRNOTAVAIL;

        sa->sat_family = AF_APPLETALK;
        sa->sat_addr.s_net = atif->address.s_net;
        sa->sat_addr.s_node = ATADDR_BCAST;
        break;

    case SIOCATALKDIFADDR:
    case SIOCDIFADDR:
        if (!capable(CAP_NET_ADMIN))
            return -EPERM;
        if (sa->sat_family != AF_APPLETALK)
            return -EINVAL;
        atalk_dev_down(dev);
        break;

    case SIOCSARP:
        if (!capable(CAP_NET_ADMIN))
            return -EPERM;
        if (sa->sat_family != AF_APPLETALK)
            return -EINVAL;
        /*
         * for now, we only support proxy AARP on ELAP;
         * we should be able to do it for LocalTalk, too.
         */
        if (dev->type != ARPHRD_ETHER)
            return -EPROTONOSUPPORT;

        /*
         * atif points to the current interface on this network;
         * we aren't concerned about its current status (at
         * least for now), but it has all the settings about
         * the network we're going to probe. Consequently, it
         * must exist.
         */
        if (!atif)
            return -EADDRNOTAVAIL;

        nr = (struct atalk_netrange *)&(atif->nets);
        /*
         * Phase 1 is fine on Localtalk but we don't do
         * Ethertalk phase 1. Anyone wanting to add it go ahead.
         */
        if (dev->type == ARPHRD_ETHER && nr->nr_phase != 2)
            return -EPROTONOSUPPORT;

        if (sa->sat_addr.s_node == ATADDR_BCAST ||
            sa->sat_addr.s_node == 254)
            return -EINVAL;

        /*
         * Check if the chosen address is used. If so we
         * error and ATCP will try another.
         */
        if (atif_proxy_probe_device(atif, &(sa->sat_addr)) < 0)
            return -EADDRINUSE;

        /*
         * We now have an address on the local network, and
         * the AARP code will defend it for us until we take it
         * down. We don't set up any routes right now, because
         * ATCP will install them manually via SIOCADDRT.
         */
        break;

    case SIOCDARP:
        if (!capable(CAP_NET_ADMIN))
            return -EPERM;
        if (sa->sat_family != AF_APPLETALK)
            return -EINVAL;
        if (!atif)
            return -EADDRNOTAVAIL;

        /* give to aarp module to remove proxy entry */
        aarp_proxy_remove(atif->dev, &(sa->sat_addr));
        return 0;
    }

    return copy_to_user(arg, &atreq, sizeof(atreq)) ? -EFAULT : 0;
}

/* Routing ioctl() calls */
static int atrtr_ioctl(unsigned int cmd, void __user *arg)
{
    struct rtentry rt;

    if (copy_from_user(&rt, arg, sizeof(rt)))
        return -EFAULT;

    switch (cmd) {
    case SIOCDELRT:
        if (rt.rt_dst.sa_family != AF_APPLETALK)
            return -EINVAL;
        return atrtr_delete(&((struct sockaddr_at *)
                      &rt.rt_dst)->sat_addr);

    case SIOCADDRT: {
        struct net_device *dev = NULL;
        if (rt.rt_dev) {
            char name[IFNAMSIZ];
            if (copy_from_user(name, rt.rt_dev, IFNAMSIZ-1))
                return -EFAULT;
            name[IFNAMSIZ-1] = '\0';
            dev = __dev_get_by_name(&init_net, name);
            if (!dev)
                return -ENODEV;
        }
        return atrtr_create(&rt, dev);
    }
    }
    return -EINVAL;
}

/**************************************************************************\
*                                                                          *
* Handling for system calls applied via the various interfaces to an       *
* AppleTalk socket object.                                                 *
*                                                                          *
\**************************************************************************/

/*
 * Checksum: This is 'optional'. It's quite likely also a good
 * candidate for assembler hackery 8)
 */
static unsigned long atalk_sum_partial(const unsigned char *data,
                       int len, unsigned long sum)
{
    /* This ought to be unwrapped neatly. I'll trust gcc for now */
    while (len--) {
        sum += *data++;
        sum = rol16(sum, 1);
    }
    return sum;
}

/*  Checksum skb data --  similar to skb_checksum  */
static unsigned long atalk_sum_skb(const struct sk_buff *skb, int offset,
                   int len, unsigned long sum)
{
    int start = skb_headlen(skb);
    struct sk_buff *frag_iter;
    int i, copy;

    /* checksum stuff in header space */
    if ( (copy = start - offset) > 0) {
        if (copy > len)
            copy = len;
        sum = atalk_sum_partial(skb->data + offset, copy, sum);
        if ( (len -= copy) == 0)
            return sum;

        offset += copy;
    }

    /* checksum stuff in frags */
    for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
        int end;
        const skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
        WARN_ON(start > offset + len);

        end = start + skb_frag_size(frag);
        if ((copy = end - offset) > 0) {
            u8 *vaddr;

            if (copy > len)
                copy = len;
            vaddr = kmap_atomic(skb_frag_page(frag));
            sum = atalk_sum_partial(vaddr + frag->page_offset +
                          offset - start, copy, sum);
            kunmap_atomic(vaddr);

            if (!(len -= copy))
                return sum;
            offset += copy;
        }
        start = end;
    }

    skb_walk_frags(skb, frag_iter) {
        int end;

        WARN_ON(start > offset + len);

        end = start + frag_iter->len;
        if ((copy = end - offset) > 0) {
            if (copy > len)
                copy = len;
            sum = atalk_sum_skb(frag_iter, offset - start,
                        copy, sum);
            if ((len -= copy) == 0)
                return sum;
            offset += copy;
        }
        start = end;
    }

    BUG_ON(len > 0);

    return sum;
}

static __be16 atalk_checksum(const struct sk_buff *skb, int len)
{
    unsigned long sum;

    /* skip header 4 bytes */
    sum = atalk_sum_skb(skb, 4, len-4, 0);

    /* Use 0xFFFF for 0. 0 itself means none */
    return sum ? htons((unsigned short)sum) : htons(0xFFFF);
}

static struct proto ddp_proto = {
    .name     = "DDP",
    .owner    = THIS_MODULE,
    .obj_size = sizeof(struct atalk_sock),
};

/*
 * Create a socket. Initialise the socket, blank the addresses
 * set the state.
 */
static int atalk_create(struct net *net, struct socket *sock, int protocol,
            int kern)
{
    struct sock *sk;
    int rc = -ESOCKTNOSUPPORT;

    if (!net_eq(net, &init_net))
        return -EAFNOSUPPORT;

    /*
     * We permit SOCK_DGRAM and RAW is an extension. It is trivial to do
     * and gives you the full ELAP frame. Should be handy for CAP 8)
     */
    if (sock->type != SOCK_RAW && sock->type != SOCK_DGRAM)
        goto out;
    rc = -ENOMEM;
    sk = sk_alloc(net, PF_APPLETALK, GFP_KERNEL, &ddp_proto);
    if (!sk)
        goto out;
    rc = 0;
    sock->ops = &atalk_dgram_ops;
    sock_init_data(sock, sk);

    /* Checksums on by default */
    sock_set_flag(sk, SOCK_ZAPPED);
out:
    return rc;
}

/* Free a socket. No work needed */
static int atalk_release(struct socket *sock)
{
    struct sock *sk = sock->sk;

    if (sk) {
        sock_hold(sk);
        lock_sock(sk);

        sock_orphan(sk);
        sock->sk = NULL;
        atalk_destroy_socket(sk);

        release_sock(sk);
        sock_put(sk);
    }
    return 0;
}

static int atalk_pick_and_bind_port(struct sock *sk, struct sockaddr_at *sat)
{
    int retval;

    write_lock_bh(&atalk_sockets_lock);

    for (sat->sat_port = ATPORT_RESERVED;
         sat->sat_port < ATPORT_LAST;
         sat->sat_port++) {
        struct sock *s;
        struct hlist_node *node;

        sk_for_each(s, node, &atalk_sockets) {
            struct atalk_sock *at = at_sk(s);

            if (at->src_net == sat->sat_addr.s_net &&
                at->src_node == sat->sat_addr.s_node &&
                at->src_port == sat->sat_port)
                goto try_next_port;
        }

        /* Wheee, it's free, assign and insert. */
        __atalk_insert_socket(sk);
        at_sk(sk)->src_port = sat->sat_port;
        retval = 0;
        goto out;

try_next_port:;
    }

    retval = -EBUSY;
out:
    write_unlock_bh(&atalk_sockets_lock);
    return retval;
}

static int atalk_autobind(struct sock *sk)
{
    struct atalk_sock *at = at_sk(sk);
    struct sockaddr_at sat;
    struct atalk_addr *ap = atalk_find_primary();
    int n = -EADDRNOTAVAIL;

    if (!ap || ap->s_net == htons(ATADDR_ANYNET))
        goto out;

    at->src_net  = sat.sat_addr.s_net  = ap->s_net;
    at->src_node = sat.sat_addr.s_node = ap->s_node;

    n = atalk_pick_and_bind_port(sk, &sat);
    if (!n)
        sock_reset_flag(sk, SOCK_ZAPPED);
out:
    return n;
}

/* Set the address 'our end' of the connection */
static int atalk_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
{
    struct sockaddr_at *addr = (struct sockaddr_at *)uaddr;
    struct sock *sk = sock->sk;
    struct atalk_sock *at = at_sk(sk);
    int err;

    if (!sock_flag(sk, SOCK_ZAPPED) ||
        addr_len != sizeof(struct sockaddr_at))
        return -EINVAL;

    if (addr->sat_family != AF_APPLETALK)
        return -EAFNOSUPPORT;

    lock_sock(sk);
    if (addr->sat_addr.s_net == htons(ATADDR_ANYNET)) {
        struct atalk_addr *ap = atalk_find_primary();

        err = -EADDRNOTAVAIL;
        if (!ap)
            goto out;

        at->src_net  = addr->sat_addr.s_net = ap->s_net;
        at->src_node = addr->sat_addr.s_node= ap->s_node;
    } else {
        err = -EADDRNOTAVAIL;
        if (!atalk_find_interface(addr->sat_addr.s_net,
                      addr->sat_addr.s_node))
            goto out;

        at->src_net  = addr->sat_addr.s_net;
        at->src_node = addr->sat_addr.s_node;
    }

    if (addr->sat_port == ATADDR_ANYPORT) {
        err = atalk_pick_and_bind_port(sk, addr);

        if (err < 0)
            goto out;
    } else {
        at->src_port = addr->sat_port;

        err = -EADDRINUSE;
        if (atalk_find_or_insert_socket(sk, addr))
            goto out;
    }

    sock_reset_flag(sk, SOCK_ZAPPED);
    err = 0;
out:
    release_sock(sk);
    return err;
}

/* Set the address we talk to */
static int atalk_connect(struct socket *sock, struct sockaddr *uaddr,
             int addr_len, int flags)
{
    struct sock *sk = sock->sk;
    struct atalk_sock *at = at_sk(sk);
    struct sockaddr_at *addr;
    int err;

    sk->sk_state   = TCP_CLOSE;
    sock->state = SS_UNCONNECTED;

    if (addr_len != sizeof(*addr))
        return -EINVAL;

    addr = (struct sockaddr_at *)uaddr;

    if (addr->sat_family != AF_APPLETALK)
        return -EAFNOSUPPORT;

    if (addr->sat_addr.s_node == ATADDR_BCAST &&
        !sock_flag(sk, SOCK_BROADCAST)) {
#if 1
        pr_warn("atalk_connect: %s is broken and did not set SO_BROADCAST.\n",
            current->comm);
#else
        return -EACCES;
#endif
    }

    lock_sock(sk);
    err = -EBUSY;
    if (sock_flag(sk, SOCK_ZAPPED))
        if (atalk_autobind(sk) < 0)
            goto out;

    err = -ENETUNREACH;
    if (!atrtr_get_dev(&addr->sat_addr))
        goto out;

    at->dest_port = addr->sat_port;
    at->dest_net  = addr->sat_addr.s_net;
    at->dest_node = addr->sat_addr.s_node;

    sock->state  = SS_CONNECTED;
    sk->sk_state = TCP_ESTABLISHED;
    err = 0;
out:
    release_sock(sk);
    return err;
}

/*
 * Find the name of an AppleTalk socket. Just copy the right
 * fields into the sockaddr.
 */
static int atalk_getname(struct socket *sock, struct sockaddr *uaddr,
             int *uaddr_len, int peer)
{
    struct sockaddr_at sat;
    struct sock *sk = sock->sk;
    struct atalk_sock *at = at_sk(sk);
    int err;

    lock_sock(sk);
    err = -ENOBUFS;
    if (sock_flag(sk, SOCK_ZAPPED))
        if (atalk_autobind(sk) < 0)
            goto out;

    *uaddr_len = sizeof(struct sockaddr_at);
    memset(&sat.sat_zero, 0, sizeof(sat.sat_zero));

    if (peer) {
        err = -ENOTCONN;
        if (sk->sk_state != TCP_ESTABLISHED)
            goto out;

        sat.sat_addr.s_net  = at->dest_net;
        sat.sat_addr.s_node = at->dest_node;
        sat.sat_port        = at->dest_port;
    } else {
        sat.sat_addr.s_net  = at->src_net;
        sat.sat_addr.s_node = at->src_node;
        sat.sat_port        = at->src_port;
    }

    err = 0;
    sat.sat_family = AF_APPLETALK;
    memcpy(uaddr, &sat, sizeof(sat));

out:
    release_sock(sk);
    return err;
}

#if defined(CONFIG_IPDDP) || defined(CONFIG_IPDDP_MODULE)
static __inline__ int is_ip_over_ddp(struct sk_buff *skb)
{
    return skb->data[12] == 22;
}

static int handle_ip_over_ddp(struct sk_buff *skb)
{
    struct net_device *dev = __dev_get_by_name(&init_net, "ipddp0");
    struct net_device_stats *stats;

    /* This needs to be able to handle ipddp"N" devices */
    if (!dev) {
        kfree_skb(skb);
        return NET_RX_DROP;
    }

    skb->protocol = htons(ETH_P_IP);
    skb_pull(skb, 13);
    skb->dev   = dev;
    skb_reset_transport_header(skb);

    stats = netdev_priv(dev);
    stats->rx_packets++;
    stats->rx_bytes += skb->len + 13;
    return netif_rx(skb);  /* Send the SKB up to a higher place. */
}
#else
/* make it easy for gcc to optimize this test out, i.e. kill the code */
#define is_ip_over_ddp(skb) 0
#define handle_ip_over_ddp(skb) 0
#endif

static int atalk_route_packet(struct sk_buff *skb, struct net_device *dev,
                  struct ddpehdr *ddp, __u16 len_hops, int origlen)
{
    struct atalk_route *rt;
    struct atalk_addr ta;

    /*
     * Don't route multicast, etc., packets, or packets sent to "this
     * network"
     */
    if (skb->pkt_type != PACKET_HOST || !ddp->deh_dnet) {
        /*
         * FIXME:
         *
         * Can it ever happen that a packet is from a PPP iface and
         * needs to be broadcast onto the default network?
         */
        if (dev->type == ARPHRD_PPP)
            printk(KERN_DEBUG "AppleTalk: didn't forward broadcast "
                      "packet received from PPP iface\n");
        goto free_it;
    }

    ta.s_net  = ddp->deh_dnet;
    ta.s_node = ddp->deh_dnode;

    /* Route the packet */
    rt = atrtr_find(&ta);
    /* increment hops count */
    len_hops += 1 << 10;
    if (!rt || !(len_hops & (15 << 10)))
        goto free_it;

    /* FIXME: use skb->cb to be able to use shared skbs */

    /*
     * Route goes through another gateway, so set the target to the
     * gateway instead.
     */

    if (rt->flags & RTF_GATEWAY) {
        ta.s_net  = rt->gateway.s_net;
        ta.s_node = rt->gateway.s_node;
    }

    /* Fix up skb->len field */
    skb_trim(skb, min_t(unsigned int, origlen,
                (rt->dev->hard_header_len +
                 ddp_dl->header_length + (len_hops & 1023))));

    /* FIXME: use skb->cb to be able to use shared skbs */
    ddp->deh_len_hops = htons(len_hops);

    /*
     * Send the buffer onwards
     *
     * Now we must always be careful. If it's come from LocalTalk to
     * EtherTalk it might not fit
     *
     * Order matters here: If a packet has to be copied to make a new
     * headroom (rare hopefully) then it won't need unsharing.
     *
     * Note. ddp-> becomes invalid at the realloc.
     */
    if (skb_headroom(skb) < 22) {
        /* 22 bytes - 12 ether, 2 len, 3 802.2 5 snap */
        struct sk_buff *nskb = skb_realloc_headroom(skb, 32);
        kfree_skb(skb);
        skb = nskb;
    } else
        skb = skb_unshare(skb, GFP_ATOMIC);

    /*
     * If the buffer didn't vanish into the lack of space bitbucket we can
     * send it.
     */
    if (skb == NULL)
        goto drop;

    if (aarp_send_ddp(rt->dev, skb, &ta, NULL) == NET_XMIT_DROP)
        return NET_RX_DROP;
    return NET_RX_SUCCESS;
free_it:
    kfree_skb(skb);
drop:
    return NET_RX_DROP;
}

static int atalk_rcv(struct sk_buff *skb, struct net_device *dev,
             struct packet_type *pt, struct net_device *orig_dev)
{
    struct ddpehdr *ddp;
    struct sock *sock;
    struct atalk_iface *atif;
    struct sockaddr_at tosat;
    int origlen;
    __u16 len_hops;

    if (!net_eq(dev_net(dev), &init_net))
        goto drop;

    /* Don't mangle buffer if shared */
    if (!(skb = skb_share_check(skb, GFP_ATOMIC)))
        goto out;

    /* Size check and make sure header is contiguous */
    if (!pskb_may_pull(skb, sizeof(*ddp)))
        goto drop;

    ddp = ddp_hdr(skb);

    len_hops = ntohs(ddp->deh_len_hops);

    /* Trim buffer in case of stray trailing data */
    origlen = skb->len;
    skb_trim(skb, min_t(unsigned int, skb->len, len_hops & 1023));

    /*
     * Size check to see if ddp->deh_len was crap
     * (Otherwise we'll detonate most spectacularly
     * in the middle of atalk_checksum() or recvmsg()).
     */
    if (skb->len < sizeof(*ddp) || skb->len < (len_hops & 1023)) {
        pr_debug("AppleTalk: dropping corrupted frame (deh_len=%u, "
             "skb->len=%u)\n", len_hops & 1023, skb->len);
        goto drop;
    }

    /*
     * Any checksums. Note we don't do htons() on this == is assumed to be
     * valid for net byte orders all over the networking code...
     */
    if (ddp->deh_sum &&
        atalk_checksum(skb, len_hops & 1023) != ddp->deh_sum)
        /* Not a valid AppleTalk frame - dustbin time */
        goto drop;

    /* Check the packet is aimed at us */
    if (!ddp->deh_dnet) /* Net 0 is 'this network' */
        atif = atalk_find_anynet(ddp->deh_dnode, dev);
    else
        atif = atalk_find_interface(ddp->deh_dnet, ddp->deh_dnode);

    if (!atif) {
        /* Not ours, so we route the packet via the correct
         * AppleTalk iface
         */
        return atalk_route_packet(skb, dev, ddp, len_hops, origlen);
    }

    /* if IP over DDP is not selected this code will be optimized out */
    if (is_ip_over_ddp(skb))
        return handle_ip_over_ddp(skb);
    /*
     * Which socket - atalk_search_socket() looks for a *full match*
     * of the <net, node, port> tuple.
     */
    tosat.sat_addr.s_net  = ddp->deh_dnet;
    tosat.sat_addr.s_node = ddp->deh_dnode;
    tosat.sat_port        = ddp->deh_dport;

    sock = atalk_search_socket(&tosat, atif);
    if (!sock) /* But not one of our sockets */
        goto drop;

    /* Queue packet (standard) */
    skb->sk = sock;

    if (sock_queue_rcv_skb(sock, skb) < 0)
        goto drop;

    return NET_RX_SUCCESS;

drop:
    kfree_skb(skb);
out:
    return NET_RX_DROP;

}

/*
 * Receive a LocalTalk frame. We make some demands on the caller here.
 * Caller must provide enough headroom on the packet to pull the short
 * header and append a long one.
 */
static int ltalk_rcv(struct sk_buff *skb, struct net_device *dev,
             struct packet_type *pt, struct net_device *orig_dev)
{
    if (!net_eq(dev_net(dev), &init_net))
        goto freeit;

    /* Expand any short form frames */
    if (skb_mac_header(skb)[2] == 1) {
        struct ddpehdr *ddp;
        /* Find our address */
        struct atalk_addr *ap = atalk_find_dev_addr(dev);

        if (!ap || skb->len < sizeof(__be16) || skb->len > 1023)
            goto freeit;

        /* Don't mangle buffer if shared */
        if (!(skb = skb_share_check(skb, GFP_ATOMIC)))
            return 0;

        /*
         * The push leaves us with a ddephdr not an shdr, and
         * handily the port bytes in the right place preset.
         */
        ddp = (struct ddpehdr *) skb_push(skb, sizeof(*ddp) - 4);

        /* Now fill in the long header */

        /*
         * These two first. The mac overlays the new source/dest
         * network information so we MUST copy these before
         * we write the network numbers !
         */

        ddp->deh_dnode = skb_mac_header(skb)[0];     /* From physical header */
        ddp->deh_snode = skb_mac_header(skb)[1];     /* From physical header */

        ddp->deh_dnet  = ap->s_net; /* Network number */
        ddp->deh_snet  = ap->s_net;
        ddp->deh_sum   = 0;     /* No checksum */
        /*
         * Not sure about this bit...
         */
        /* Non routable, so force a drop if we slip up later */
        ddp->deh_len_hops = htons(skb->len + (DDP_MAXHOPS << 10));
    }
    skb_reset_transport_header(skb);

    return atalk_rcv(skb, dev, pt, orig_dev);
freeit:
    kfree_skb(skb);
    return 0;
}

static int atalk_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg,
             size_t len)
{
    struct sock *sk = sock->sk;
    struct atalk_sock *at = at_sk(sk);
    struct sockaddr_at *usat = (struct sockaddr_at *)msg->msg_name;
    int flags = msg->msg_flags;
    int loopback = 0;
    struct sockaddr_at local_satalk, gsat;
    struct sk_buff *skb;
    struct net_device *dev;
    struct ddpehdr *ddp;
    int size;
    struct atalk_route *rt;
    int err;

    if (flags & ~(MSG_DONTWAIT|MSG_CMSG_COMPAT))
        return -EINVAL;

    if (len > DDP_MAXSZ)
        return -EMSGSIZE;

    lock_sock(sk);
    if (usat) {
        err = -EBUSY;
        if (sock_flag(sk, SOCK_ZAPPED))
            if (atalk_autobind(sk) < 0)
                goto out;

        err = -EINVAL;
        if (msg->msg_namelen < sizeof(*usat) ||
            usat->sat_family != AF_APPLETALK)
            goto out;

        err = -EPERM;
        /* netatalk didn't implement this check */
        if (usat->sat_addr.s_node == ATADDR_BCAST &&
            !sock_flag(sk, SOCK_BROADCAST)) {
            goto out;
        }
    } else {
        err = -ENOTCONN;
        if (sk->sk_state != TCP_ESTABLISHED)
            goto out;
        usat = &local_satalk;
        usat->sat_family      = AF_APPLETALK;
        usat->sat_port        = at->dest_port;
        usat->sat_addr.s_node = at->dest_node;
        usat->sat_addr.s_net  = at->dest_net;
    }

    /* Build a packet */
    SOCK_DEBUG(sk, "SK %p: Got address.\n", sk);

    /* For headers */
    size = sizeof(struct ddpehdr) + len + ddp_dl->header_length;

    if (usat->sat_addr.s_net || usat->sat_addr.s_node == ATADDR_ANYNODE) {
        rt = atrtr_find(&usat->sat_addr);
    } else {
        struct atalk_addr at_hint;

        at_hint.s_node = 0;
        at_hint.s_net  = at->src_net;

        rt = atrtr_find(&at_hint);
    }
    err = ENETUNREACH;
    if (!rt)
        goto out;

    dev = rt->dev;

    SOCK_DEBUG(sk, "SK %p: Size needed %d, device %s\n",
            sk, size, dev->name);

    size += dev->hard_header_len;
    release_sock(sk);
    skb = sock_alloc_send_skb(sk, size, (flags & MSG_DONTWAIT), &err);
    lock_sock(sk);
    if (!skb)
        goto out;

    skb->sk = sk;
    skb_reserve(skb, ddp_dl->header_length);
    skb_reserve(skb, dev->hard_header_len);
    skb->dev = dev;

    SOCK_DEBUG(sk, "SK %p: Begin build.\n", sk);

    ddp = (struct ddpehdr *)skb_put(skb, sizeof(struct ddpehdr));
    ddp->deh_len_hops  = htons(len + sizeof(*ddp));
    ddp->deh_dnet  = usat->sat_addr.s_net;
    ddp->deh_snet  = at->src_net;
    ddp->deh_dnode = usat->sat_addr.s_node;
    ddp->deh_snode = at->src_node;
    ddp->deh_dport = usat->sat_port;
    ddp->deh_sport = at->src_port;

    SOCK_DEBUG(sk, "SK %p: Copy user data (%Zd bytes).\n", sk, len);

    err = memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len);
    if (err) {
        kfree_skb(skb);
        err = -EFAULT;
        goto out;
    }

    if (sk->sk_no_check == 1)
        ddp->deh_sum = 0;
    else
        ddp->deh_sum = atalk_checksum(skb, len + sizeof(*ddp));

    /*
     * Loopback broadcast packets to non gateway targets (ie routes
     * to group we are in)
     */
    if (ddp->deh_dnode == ATADDR_BCAST &&
        !(rt->flags & RTF_GATEWAY) && !(dev->flags & IFF_LOOPBACK)) {
        struct sk_buff *skb2 = skb_copy(skb, GFP_KERNEL);

        if (skb2) {
            loopback = 1;
            SOCK_DEBUG(sk, "SK %p: send out(copy).\n", sk);
            /*
             * If it fails it is queued/sent above in the aarp queue
             */
            aarp_send_ddp(dev, skb2, &usat->sat_addr, NULL);
        }
    }

    if (dev->flags & IFF_LOOPBACK || loopback) {
        SOCK_DEBUG(sk, "SK %p: Loop back.\n", sk);
        /* loop back */
        skb_orphan(skb);
        if (ddp->deh_dnode == ATADDR_BCAST) {
            struct atalk_addr at_lo;

            at_lo.s_node = 0;
            at_lo.s_net  = 0;

            rt = atrtr_find(&at_lo);
            if (!rt) {
                kfree_skb(skb);
                err = -ENETUNREACH;
                goto out;
            }
            dev = rt->dev;
            skb->dev = dev;
        }
        ddp_dl->request(ddp_dl, skb, dev->dev_addr);
    } else {
        SOCK_DEBUG(sk, "SK %p: send out.\n", sk);
        if (rt->flags & RTF_GATEWAY) {
            gsat.sat_addr = rt->gateway;
            usat = &gsat;
        }

        /*
         * If it fails it is queued/sent above in the aarp queue
         */
        aarp_send_ddp(dev, skb, &usat->sat_addr, NULL);
    }
    SOCK_DEBUG(sk, "SK %p: Done write (%Zd).\n", sk, len);

out:
    release_sock(sk);
    return err ? : len;
}

static int atalk_recvmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg,
             size_t size, int flags)
{
    struct sock *sk = sock->sk;
    struct sockaddr_at *sat = (struct sockaddr_at *)msg->msg_name;
    struct ddpehdr *ddp;
    int copied = 0;
    int offset = 0;
    int err = 0;
    struct sk_buff *skb;

    skb = skb_recv_datagram(sk, flags & ~MSG_DONTWAIT,
                        flags & MSG_DONTWAIT, &err);
    lock_sock(sk);

    if (!skb)
        goto out;

    /* FIXME: use skb->cb to be able to use shared skbs */
    ddp = ddp_hdr(skb);
    copied = ntohs(ddp->deh_len_hops) & 1023;

    if (sk->sk_type != SOCK_RAW) {
        offset = sizeof(*ddp);
        copied -= offset;
    }

    if (copied > size) {
        copied = size;
        msg->msg_flags |= MSG_TRUNC;
    }
    err = skb_copy_datagram_iovec(skb, offset, msg->msg_iov, copied);

    if (!err) {
        if (sat) {
            sat->sat_family      = AF_APPLETALK;
            sat->sat_port        = ddp->deh_sport;
            sat->sat_addr.s_node = ddp->deh_snode;
            sat->sat_addr.s_net  = ddp->deh_snet;
        }
        msg->msg_namelen = sizeof(*sat);
    }

    skb_free_datagram(sk, skb); /* Free the datagram. */

out:
    release_sock(sk);
    return err ? : copied;
}


/*
 * AppleTalk ioctl calls.
 */
static int atalk_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
{
    int rc = -ENOIOCTLCMD;
    struct sock *sk = sock->sk;
    void __user *argp = (void __user *)arg;

    switch (cmd) {
        /* Protocol layer */
        case TIOCOUTQ: {
            long amount = sk->sk_sndbuf - sk_wmem_alloc_get(sk);

            if (amount < 0)
                amount = 0;
            rc = put_user(amount, (int __user *)argp);
            break;
        }
        case TIOCINQ: {
            /*
             * These two are safe on a single CPU system as only
             * user tasks fiddle here
             */
            struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
            long amount = 0;

            if (skb)
                amount = skb->len - sizeof(struct ddpehdr);
            rc = put_user(amount, (int __user *)argp);
            break;
        }
        case SIOCGSTAMP:
            rc = sock_get_timestamp(sk, argp);
            break;
        case SIOCGSTAMPNS:
            rc = sock_get_timestampns(sk, argp);
            break;
        /* Routing */
        case SIOCADDRT:
        case SIOCDELRT:
            rc = -EPERM;
            if (capable(CAP_NET_ADMIN))
                rc = atrtr_ioctl(cmd, argp);
            break;
        /* Interface */
        case SIOCGIFADDR:
        case SIOCSIFADDR:
        case SIOCGIFBRDADDR:
        case SIOCATALKDIFADDR:
        case SIOCDIFADDR:
        case SIOCSARP:      /* proxy AARP */
        case SIOCDARP:      /* proxy AARP */
            rtnl_lock();
            rc = atif_ioctl(cmd, argp);
            rtnl_unlock();
            break;
    }

    return rc;
}


#ifdef CONFIG_COMPAT
static int atalk_compat_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
{
    /*
     * SIOCATALKDIFADDR is a SIOCPROTOPRIVATE ioctl number, so we
     * cannot handle it in common code. The data we access if ifreq
     * here is compatible, so we can simply call the native
     * handler.
     */
    if (cmd == SIOCATALKDIFADDR)
        return atalk_ioctl(sock, cmd, (unsigned long)compat_ptr(arg));

    return -ENOIOCTLCMD;
}
#endif


static const struct net_proto_family atalk_family_ops = {
    .family     = PF_APPLETALK,
    .create     = atalk_create,
    .owner      = THIS_MODULE,
};

static const struct proto_ops atalk_dgram_ops = {
    .family     = PF_APPLETALK,
    .owner      = THIS_MODULE,
    .release    = atalk_release,
    .bind       = atalk_bind,
    .connect    = atalk_connect,
    .socketpair = sock_no_socketpair,
    .accept     = sock_no_accept,
    .getname    = atalk_getname,
    .poll       = datagram_poll,
    .ioctl      = atalk_ioctl,
#ifdef CONFIG_COMPAT
    .compat_ioctl   = atalk_compat_ioctl,
#endif
    .listen     = sock_no_listen,
    .shutdown   = sock_no_shutdown,
    .setsockopt = sock_no_setsockopt,
    .getsockopt = sock_no_getsockopt,
    .sendmsg    = atalk_sendmsg,
    .recvmsg    = atalk_recvmsg,
    .mmap       = sock_no_mmap,
    .sendpage   = sock_no_sendpage,
};

static struct notifier_block ddp_notifier = {
    .notifier_call  = ddp_device_event,
};

static struct packet_type ltalk_packet_type __read_mostly = {
    .type       = cpu_to_be16(ETH_P_LOCALTALK),
    .func       = ltalk_rcv,
};

static struct packet_type ppptalk_packet_type __read_mostly = {
    .type       = cpu_to_be16(ETH_P_PPPTALK),
    .func       = atalk_rcv,
};

static unsigned char ddp_snap_id[] = { 0x08, 0x00, 0x07, 0x80, 0x9B };

/* Export symbols for use by drivers when AppleTalk is a module */
EXPORT_SYMBOL(atrtr_get_dev);
EXPORT_SYMBOL(atalk_find_dev_addr);

static const char atalk_err_snap[] __initconst =
    KERN_CRIT "Unable to register DDP with SNAP.\n";

/* Called by proto.c on kernel start up */
static int __init atalk_init(void)
{
    int rc = proto_register(&ddp_proto, 0);

    if (rc != 0)
        goto out;

    (void)sock_register(&atalk_family_ops);
    ddp_dl = register_snap_client(ddp_snap_id, atalk_rcv);
    if (!ddp_dl)
        printk(atalk_err_snap);

    dev_add_pack(&ltalk_packet_type);
    dev_add_pack(&ppptalk_packet_type);

    register_netdevice_notifier(&ddp_notifier);
    aarp_proto_init();
    atalk_proc_init();
    atalk_register_sysctl();
out:
    return rc;
}
module_init(atalk_init);

/*
 * No explicit module reference count manipulation is needed in the
 * protocol. Socket layer sets module reference count for us
 * and interfaces reference counting is done
 * by the network device layer.
 *
 * Ergo, before the AppleTalk module can be removed, all AppleTalk
 * sockets be closed from user space.
 */
static void __exit atalk_exit(void)
{
#ifdef CONFIG_SYSCTL
    atalk_unregister_sysctl();
#endif /* CONFIG_SYSCTL */
    atalk_proc_exit();
    aarp_cleanup_module();  /* General aarp clean-up. */
    unregister_netdevice_notifier(&ddp_notifier);
    dev_remove_pack(&ltalk_packet_type);
    dev_remove_pack(&ppptalk_packet_type);
    unregister_snap_client(ddp_dl);
    sock_unregister(PF_APPLETALK);
    proto_unregister(&ddp_proto);
}
module_exit(atalk_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Alan Cox <[email protected]>");
MODULE_DESCRIPTION("AppleTalk 0.20\n");
MODULE_ALIAS_NETPROTO(PF_APPLETALK);